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Is it possible to find information about host machine from inside virtual machine?

For example its IP.

EDIT: One thing that I have found so far is:

HKLM\SOFTWARE\Microsoft\Virtual Machine\Guest\Parameters contains

  • HostName
  • PhysicalHostName
  • PhysicalHostNameFullyQualified


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Generally speaking, no. Are you asking with reference to a particular host, VM and virtualization package? – MartW Oct 8 '09 at 17:51
Windows 2008 Hyper-V – alex Oct 8 '09 at 18:09
Does your edit answer your question? HKLM\Software\Microsoft\VirtualMachine\Guest has key info about the host server. That's set with the Integration Services. To find out the IP, you could ping the PhysicalHostNameFullyQualified value. – Scott Forsyth - MVP Oct 8 '09 at 20:46
up vote 3 down vote accepted

The ideal answer (from a VM management perspective) to this is that you shouldn't be able to tell anything about the physical host unless that information has explicitly been made available to you. In practice VM installations tend to leak some information about the host, mostly because customized ( and often paravirtualized) drivers are installed that provide better VM performance. The default setup of VM environments will usually provide some basic information in various places (like the Hyper-V data you list).

While there are some scenarios where I can see legitimate reasons for wanting to do this (e.g. a VM in a cluster checking to see if the host its running on is actually delivering all the physical resources the VM believes it has before kicking off a high load but low priority task) almost all cases where a VM "wants" to figure out more about its host are malicious. If there is a valid reason for a process running in a VM to know this type of info then its a trivial task to set up a legitimate mechanism to provide that information to it - for the most part as a VM admin I don't want the VM's to be able to tell any of this.

This post from the Sourcefire VRT outlines some of the mechanisms that are used by Malware to detect whether they are running in a VM and the mitigation actions that can be taken to counter them - for the most part a VM can pretty much always tell that it is running in a VM and can usually tell the Hypervisor Vendor, probably identify the Hypervisor type and possibly make a good guess as to the specific version. Some additional info can usually be gathered from the network but that would almost certainly be the sort of activity that should be classified as malicious. If you read that post you will see that it is possible to configure a VM so that it is very hard for anything running in the VM to figure out anything other than the basic fact that it is a VM so relying on these mechanisms is a bad idea.

On your specific question about the "ip-address" of the Hypervisor the general answer would be that Hypervisors can have many ip-addresses - the Management console, iSCSI ports, Live Motion\Fault Tolerance ports and many ports that don't have explicit ip-addresses (VM ports) and other variations. Finding the management console ip-address(es) may be trivial - as per your Hyper-V example - but doing anything with it should be hard, in a well designed VM infrastructure the VM's shouldn't be able to route to the Management console address.

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Hi Helvick - I think your answer is good from a theoretical perspective of whether/if VM guests "know" about their hosts, but there are definitely ways in practice. – Matt Oct 25 '09 at 21:42

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Virtual Machine\Guest\Parameters key in the Registry of a virtual machine lists information of hyper-v host machines. I've a windows 2003 VM running on a hyper-v host 2008 R2 server. I can see the host machine name in the registry of 2003 vm.

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You've identified exactly what you were looking for, I think. That registry key is the way that Hyper-V gives you information about the host machine.

The only thing you need to remember when you write code that uses it is that it can be wrong by the time you consume it, as your VM may be saved and then restored or it may migrate while whatever code or script you've written is executing.

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Pretty much no. The guest OS has no access to the host machine. Why do want your guest talking to the host?

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I don't need access to host machine, I need information about host machine – alex Oct 8 '09 at 18:20
I don't think there's a way to figure out which host you are on without running a query against the management system. If you have the management pack (the name escapes me at the moment) you could probably run a WMI query against it to find out which host you are on. That or query the SQL Database behind it. – mrdenny Oct 8 '09 at 18:31

For security reasons, I'm sure the answer is no. Unless you create a Host-only network connection in which you can get access to the host through the network. The idea is, the host has to grant you access to its information first.

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Check out libvirt. It seems to be mostly server-side-orientated, but does have some client side features (or at least plans to include them) for things like finding PCI slots used on the server from the client in order to assume take control of, say, a sound card.

If you just want to find out something simple like whether you're running in a VM or what kind of VM, it's probably easiest to do that by looking at the virtual machine's BIOS ID or other device identifier strings.

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While a virtual machine guest theoretically doesn't "know" anything about it's host (it generally doesn't even know it's even a VM), you can get information about the host by simply treating the host as just another machine on the network, from the point of view of the guest. This assumes that the guest can see the host on the network.

Once you have network access (and proper credentials) to the host you have a number of options to gather information:

psexec \\host_computer_name ipconfig

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